Rabbits no longer need sand/grass in order to spawn in deserts/tundras

Pretty much the title. Rabbits can now spawn on any blocks in deserts or tundras.

The simplest way to test this is to create a new superflat world with the "redstone ready" preset and wait a bit. One can test if rabbits have spawned by running /execute if entity @e[type=rabbit] in chat and inspecting the result.